Should You Let Your Baby Cry It Out?

In my work with thousands of families, I've found that babies can learn healthy sleep habits without being left alone in distress. Yet many parents never hear about those alternatives. Instead, they're told that crying is unavoidable—or even necessary—for healthy sleep.

Many loving parents turn to cry-it-out sleep training because they're desperate for sleep. I understand that desperation. Sleep deprivation affects your mood, your health, your relationships, and your ability to be the parent you want to be.

But before you decide that crying it out is your only option, it's important to know two things:

1. There are gentler ways to help babies learn healthy sleep habits.
2. There are legitimate developmental reasons to be cautious about leaving babies to cry without comfort.

What Is "Cry It Out"?

The phrase "cry it out" is used to describe a range of sleep-training methods. Some involve leaving a baby to cry without returning. Others, such as the well-known Ferber method, involve returning at increasing intervals to briefly reassure the baby before leaving again.

The common element is that the baby is expected to fall asleep without being comforted in the way they are asking to be comforted—usually by being held, rocked, nursed, or reassured by a parent.

The goal is for the baby to learn to fall asleep independently.

The question is not whether this approach can reduce crying over time. It often does.

The question is what the baby may be learning in the process.

How Babies Learn To Soothe Themselves

One of the most important things we've learned from developmental neuroscience is that self-regulation develops from co-regulation.

Babies are not born able to calm themselves when they are frightened, lonely, overwhelmed, or distressed. Their brains are still developing the neural pathways that make self-regulation possible.

Those pathways are built through repeated experiences of being soothed.

1. A baby cries.
2. A caring adult responds.
3. The baby's nervous system settles.

Over time, those thousands of experiences become the foundation for the child's own ability to calm herself.

In other words, babies don't learn self-soothing by being left alone with overwhelming feelings. They learn self-soothing because someone has soothed them so many times that they gradually internalize the experience.

That's why many developmental psychologists and attachment researchers have concerns about approaches that ask babies to cope with significant distress without parental comfort.

What Does The Research Say?

Research on sleep training is often presented as though the issue is settled. It isn't.

Many studies find that sleep-trained babies eventually cry less at bedtime and that parents report improvements in their own sleep and stress levels. That's important.

But a different question has received far less attention:

What is happening inside the baby while this learning is taking place?

One of the most frequently discussed studies addressing that question was conducted by Wendy Middlemiss and her colleagues.

Researchers measured cortisol—a hormone associated with stress—in both mothers and babies during a sleep-training program.

The first night, babies cried and their cortisol levels rose sharply, which was not surprising.

What happened next was more intriguing.

By the third night, many babies had largely stopped crying at bedtime. Their mothers understandably interpreted this as a sign that the babies had adjusted to the new routine and were happily falling asleep without protest.

But the babies' cortisol levels remained elevated.

In other words, the babies appeared calm, but physiologically they were still showing signs of distress.

At the same time, mothers' cortisol levels had dropped, suggesting that mothers were feeling less stressed while their babies' bodies were still mounting a stress response.

So when a baby cries and no one comes, they may eventually stop crying. But that doesn’t necessarily mean they’ve learned to calm themselves.

Other studies using objective sleep measures confirm that even after sleep training, babies often continue to wake during the night, just as they did before the sleep training. They just don’t cry. In other words, sleep training teaches babies not to call for help, not how to sleep.

The idea of a baby lying silent and anxious, alone in the dark, is distressing. And many families find they need to repeat some form of training during developmental leaps, illness, travel, or major transitions.

At the same time, we don’t yet have strong evidence about long-term emotional outcomes, especially for very young infants.

The Middlemiss study was relatively small and, like all research, has limitations. But it raises an important question:

Is a baby who has stopped crying necessarily a baby who no longer needs comfort?

Or has the baby simply learned not to call for help, since no one will come?

Middlemiss does not answer that question definitively. But it is one reason many developmental specialists remain cautious about sleep-training approaches that rely on leaving babies to cry.

Earlier Research Raises Similar Concerns

The Middlemiss study is not the only source of concern.

For decades, researchers studying attachment, stress physiology, and early brain development have documented the importance of responsive caregiving during infancy.

We know that when babies experience prolonged distress, stress hormones rise. We know that repeated experiences of comfort help organize the developing nervous system. We know that sensitive, responsive caregiving is associated with more secure attachment and better emotional regulation later in childhood.

What we don't know with certainty is exactly where the threshold lies between manageable frustration and distress that may be too much for a particular baby.

Babies differ. Families differ. Circumstances differ.

But the broader body of developmental research consistently points in the same direction: young children do best when the adults who care for them respond to their emotional needs with warmth, sensitivity, and comfort.

When distress is met with comfort, babies build the neural pathways for self-regulation. Over time, that repeated experience of being soothed becomes the ability to soothe themselves. In other words, babies don’t learn to soothe themselves by being left alone—they learn it by being soothed, over and over again.

The concern is not that babies cry. The concern is what happens when a baby repeatedly cries for comfort and that comfort doesn't come.

Human babies are born expecting protection, connection, and responsiveness from the adults who care for them. When they are frightened, lonely, overwhelmed, or distressed, they signal for help. That's how our species survives. When a parent responds, the baby's nervous system learns an important lesson: When I am distressed, help is available. Relationships are a source of safety.

But when a baby repeatedly signals for comfort and no comfort comes, the lesson may be very different.

The goal of healthy development is to help children develop the inner resources that eventually allow them to handle disappointment, frustration, fear, and loneliness without becoming overwhelmed. Neuroscience tells us that means helping babies internalize the experience of comfort so that, over time, they can comfort themselves. 

If you’d like a step-by-step guide to helping your baby sleep without leaving them to cry—and a deeper look at the research—you’ll find that at Teaching Your Baby to Fall Asleep Without Crying It Out.

What if you’ve already sleep-trained using “cry it out”? Don’t panic. You were doing the best you could with the information and support you had at the time. And the good news is that your relationship with your child is built day by day. Every moment of connection and responsiveness helps your child feel safe and secure.